Object Representation in Infants' Coordination of Manipulative Force

Abstract

This study examined infants' use of object knowledge for scaling the manipulative force of object-directed actions. Infants 9, 12, and 15 months of age were outfitted with motion-analysis sensors on their arms and then presented with stimulus objects to examine individually over a series of familiarization trials. Two stimulus objects were used in the familiarization phase, and were identical in size, shape, and material, but different in color and weight. Following familiarization, two test objects that had been hidden from view were presented. The test objects were identical in appearance to the familiarization objects, but their color-weight correspondence was reversed. Infants' actions on the test objects revealed selective, differential preparation for the specific weights experienced during familiarization. Because the objects were equivalent in their visual affordances for action, the differential preparation and coordination of manipulative force was based on knowledge acquired during the familiarization phase. Infants are capable of utilizing object representations to coordinate manipulative force in object-directed actions.Send correspondence to Clay Mash, NICHD,

Infants in Control: Prospective Motor Control and Executive Functions in Action Development

“…More generally, weight perception was studied in weightlifting paradigms measuring verbal judgments (Davis & Roberts, 1976), electromyography (EMG; Schmitz, Martin, & Assaiante, 1999), force (Buckingham, Goodale, et al, 2016;Li, Randerath, Goldenberg, & Hermsdörfer, 2011) or reaching and lifting kinematics (Mash, 2007), and in action observation paradigms measuring electroencephalography (EEG; Upshaw, Bernier, & Sommerville, 2015), functional magnetic resonance imaging (fMRI; Grezes, Frith, & Passingham, 2004), transcranial magnetic stimulation (TMS; Alaerts, Swinnen, & Wenderoth, 2010), force (Reichelt, Ash, Baugh, Johansson, & Flanagan, 2013), or own action performance (Hamilton, Wolpert, Frith, & Grafton, 2006). However, the mechanisms underlying the so-called illusion 10 are still debated.…”

“…One classical way of studying the questions of ambiguous sensory information is to present participants with objects with certain weights that additionally differ in color (Mash, 2007), size , material 59 (Paulus & Hauf, 2011) or shape (Mash, Bornstein, & Banerjee, 2014). 21 A lifting task, where object weight is indicated by visual and non-visual information, such as tactile and sensorimotor memory information, can reveal prospective control processes of the involved movements (Buckingham & Goodale, 2010;Flanagan, Bowman, & Johansson, 2006).…”

“…21 A lifting task, where object weight is indicated by visual and non-visual information, such as tactile and sensorimotor memory information, can reveal prospective control processes of the involved movements (Buckingham & Goodale, 2010;Flanagan, Bowman, & Johansson, 2006). Study I used a paradigm inspired by the work of Marshall, Saby, and Meltzoff (2013) and Mash (2007): Fourteen-month-olds participated in one of two conditions, where they were given different weighted objects (one light and one heavy object) for lifting and shaking -one object at a time of a pair. In the different color condition they lifted two objects that differed in color, where different colors indicated different object weight, serving as a visual cue before manual contact.…”

“…Lifting amplitude at the end of the first movement unit served as early indicator of prospective control before possible proprioceptive feedback processes influence the current lifting action (Jeannerod, 1988). Using this methodology enabled us to choose a measurement that is directly related to the inherent structure of every single movement, instead of applying a fixed time criterion (as Mash, 2007) or having to rely on the end state of every movement. The particular age group was chosen, because infants at this age are able to use color cues for object differentiation (Mash, 2007).…”

“…Using this methodology enabled us to choose a measurement that is directly related to the inherent structure of every single movement, instead of applying a fixed time criterion (as Mash, 2007) or having to rely on the end state of every movement. The particular age group was chosen, because infants at this age are able to use color cues for object differentiation (Mash, 2007). We had the following hypotheses ( Figure 7): 1) Based on previous work (Mash, 2007), we expected infants in the different color condition to lift the light object higher than the heavy object at the end of the first movement unit.…”